Miss on acceleration
07-23-2007, 12:43 PM
#1
Pro
Thread Starter
Miss on acceleration
Just got 86 na back on the road, now I have a miss on hard acceleration. Fuel pressure is good, wideband A/F meter looks like it might be running lean. If I gradually come up to higher rpm's it runs ok. Is there an easy way to richen it up under acceleration ?
07-23-2007, 01:21 PM
#2
Rennlist Member
check your distributor cap, rotor and wires. Ive had a couple cars w/ NEW wires that missed hard under full accelleration and fine otherwords. Ended up the wires were bad. Could also have a nasty spot on the afm where the sensor rides under that black cap- had that on the 924s once- cleaned it w/ some steel wool and alcohol worked great.
07-23-2007, 03:37 PM
#3
Racer
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Also check out your reference sensor connections and wires. I had a problem with mine this weekend, which acted like a rev-limiter at 5500 RPM, and another racer had a similar issue at 5000. I would pull off the track and wiggle the wires, and then it would go away for a little bit. This is with new sensors too, so my problem is somewhere in the wiring harness that goes to the DME.
07-24-2007, 11:16 AM
#4
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I have a similiar issue with my '87 NA. Under accleration it has these hesitations or misses. Not bad, very sutle. I have replaced the plug wires, plugs, O2 sensor and both reference sensors and it is still there. Any other ideas? It is very mild but it sure does drive me crazy.
Chris
'87 944 NA
Austin, TX
Chris
'87 944 NA
Austin, TX
07-24-2007, 12:55 PM
#5
Burning Brakes
Originally Posted by Weston
Also check out your reference sensor connections and wires. I had a problem with mine this weekend, which acted like a rev-limiter at 5500 RPM, and another racer had a similar issue at 5000. I would pull off the track and wiggle the wires, and then it would go away for a little bit. This is with new sensors too, so my problem is somewhere in the wiring harness that goes to the DME.
07-24-2007, 01:14 PM
#6
Rennlist Member
Well, you can rule out the AFM by going WOT. The DME doesn't use the AFM under that condition. If it still misses, then you need to look elsewhere. You say fuel pressure is good, but was that static fuel pressure? Your fuel filter may be restricting flow just enough under hard acceleration to not provide enough fuel.
07-24-2007, 02:05 PM
#7
Drifting
Originally Posted by Funn944
Just got 86 na back on the road, now I have a miss on hard acceleration. Fuel pressure is good, wideband A/F meter looks like it might be running lean. If I gradually come up to higher rpm's it runs ok. Is there an easy way to richen it up under acceleration ?
1) Remove the J-Boot from between the AFM and the throttle body and check for hairline cracks or tears in between the folds; check for vacumn leaks as well by spraying a controlled amount of your favourite starting fluid near the hoses under the intake manifold.
2) Are you are using Bosch platinum spark plugs or any other plugs other than the ones in the manual get rid of them and replace with OEM.
